2/10/2024 0 Comments Shunt vs dead space question![]() ![]() ![]() Tests assessing gas exchange showed: a) low hemoglobin-corrected DL CO and carbon monoxide transfer coefficient (K CO) with normal alveolar ventilation (V A) and V A/TLC ratio b) mildly reduced PaO 2 and eucapnia and c) high alveolar-arterial gradient pressure of O 2, shunt fraction (on 100% O 2), physiological dead space, arterial to end-tidal carbon dioxide gradient, and resting o VE/VCO 2ratio. A six-minute walk test confirmed poor exercise tolerance with high dyspnea burden and exertional hypoxemia. Her dyspnea has been ascribed to sedentary lifestyle and severe anemia in the context of multiple myeloma. OVERVIEWĪ 71-year-old current smoker woman was referred to the pulmonology clinic due to progressing exertional dyspnea (modified Medical Research Council score = 3/4) despite normal spirometry, lung volumes, and contrast-enhanced chest CT results. Due to the ominous systemic consequences of impaired pulmonary gas exchange, tests addressing its multifaceted features are germane to the practice of Pulmonology. Clinical Exercise Physiology: Theory and Practice. Of note, arterial blood gases are influenced not only by the integrity of the alveolar-capillary membrane but also by hemodynamic factors (e.g., poor peripheral tissue perfusion leading to low mixed venous O 2 pressure) and changes in ventilatory drive (e.g., hypoventilation leading to hypercapnia and hypoxemia) among others. Most of the pulmonary function tests, however, explore potential abnormalities in a step that precedes alveolar gas exchange, i.e., ventilation (VE). The lungs are the organs responsible for maintaining an adequate PaCO 2 for the level of CO 2 production (VCO 2) while avoiding critical decrements in PaO 2. The human body is primarily concerned with the stability of pH. ![]()
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